Cyclonic storm surges constitute a major threat to lives and properties along the vast coastline of the Bengal delta. From a combination of cyclone and storm surge modelling, we present a robust probabilistic estimate of the storm surge flooding hazard under the current climate. The estimated extreme water levels vary regionally, and the inland flooding is strongly controlled by the embankments. More than 1/10 of the coastal population is currently exposed to 50-year return period flooding.